Explosionproof lighting fixture



Jan. 1,1946.

N. A. TORNBLOM EXPLOSIONPROOF LIGHTING FIXTURE I 2 Sheets-Sheet. 1

' Filed July 24,.1942

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EXPLOSIONPRQOF LIGHTING FIXTURE Filed July 24, 1942 I 2 Sheets-Sheet 2 li'wv r irzvemfor A; Torlzfilom' Patented Jan. 1, 1946 UNITED STATES PATENT OFFICE EXPLOSIONPROOF LIGHTING FIXTURE Nils A. Tornblom,

ton Electric Company, Chicago,

tion of Illinois Chicago, Ill., assignor to Apple- IIL, a corpora- Application July 24, 1942, Serial No. 452,154 8 Claims. (or. 240-112) My invention relates generally to an proof lighting fixture for supporting one or more An illuminating device of this character customarily employs a so-called starting switch able gases and the novel means by which said objects are eireetuated will be definitely pointed out in the claims.

In the drawings: A

Figure 1 is a perspective view of my improved Fig. 2 is a vertical sectional elevation of one end of the fixture.

Fig. 3 is an end view partly in section looking in the direction of the arrow I in Fig. 2.

Figs. 4 and 5 are sections along the lines 4- and 5-5, respectively, in Fig. 2 showing certain details of construction. v

In describing the fixture, it will be understood that the construction shown in Fig. 2 is duplicated at the other end 01' the fixture except for and that the fixture may be oi the invention,

number oi lighting tubes, in-

arranged 101 any objects of my invention will eluding one tube, instead of the two tubes actually illustrated;

Referring to Fig. 2, the a hol recessed in two locations as at 2| to receive the externally flared ends 01' sleeves 22 that are secured and sealedly connected to the support 20 5 23 appropriately as Pyrex, and is light-pervious, being transparent, translucent or colored as desired.

' headed lastenings 30 which are The electric circuit which is also conventional forms no part of the present invention and hence not been particularly illustrated or described. 5 For present p ses, it will b understood that inner ends ecured to 1y threaded portion provides a very effective medium ends or a pair of conductors 38 are also soldered or otherwise secured to the connectors II and their Opposite ends to the starter 21. It will be understood that an insulating plug similar to the plug 31 is employed in a similar location at the other end of the fixture and conductors similar ot the conductors 3B are connected to an electrode (not shown) which is mounted in the opposite end of the tube 24. Handhole covers 39 and ID are threadedly mounted in convenient wall portions of the casing l and facilitate the attachment of the wires and for other purposes. A hood ll may be connected to the casings III to provide a decorative and dust cover for the housing I4 and sleeves 22.

From the foregoing, the interiors of the casings Ill, housing ll and conduits l8 are in communication with each other and form in effect a, single enclosure means, while a second enclosure means is constituted by the interiors of the supports 20 and sleeves 22. A31 important feature of the invention resides in the fact that the threaded connections of the pipes II and 12 to the end casings i0 and to the ceiling fixtures (not shown), the threaded connections or the conduits it to the casings l0 and housing It, the threaded connections of the end supports 20 to the extensions is, the threaded connections of the insulating plugs 31 to the some extensions and the threaded connections of the covers 89 and ill all have a sufiicient number of threads to prevent the passage or flame in either direction. A similar function is performed by the ground mating surfaces of the housing parts It and I6. Accordlns y. the two general enclosure means, as defined above, are each flame sealed from the atmosphere and are e sealed from each other by the 81. Hence, any explosions that may occur within eith'er enclosure means are respectively localized from each other and from the atmosphere.

Another important feature 01' the invention resides in the mounting of the lighting tube 24 within the sleeve 12 so that an annular air space exists therebetween. The column 01 air in this space for absorbing or cushioning any explosions that may take place in the end support 20 due to arcing or the starter. This cushioning action absorbs any strain that might otherwise be exerted by these explosions and hence protects the apparatus.

The reference in the claims to a "lighting fixture of the fluorescent typeor to a fluorescent lighting fixture" generally includes fixtures in 1 which illumination is achieved by an electrical discharge through gas or vapor-filled tubes.

I claim as my invention:

1. A fluorescent lightinglfixture comprising in combination, end members each having first and second chambers, a seal between the chambers, a transformer housing disposed between the members and connected to the first chambers by conduits, the chambers, housing and conduits, being insulatin p u s housing i4 through the latter in turn being threaded in the internalj of the extension is. Th'e support 20 in order to it will be apparent that casing, means sealing sealed from the atmosphere, lar member impervious to bridged between and having its ends sealed in walls of the second chambers, means for supporting a lighting tube in position to extend through the tubular member in spaced relation thereto. and electrical starting means'for the tube in one or the second chambers having conductors extending through the seal between the adjacent chambers.

2. A fluorescent lighting fixture comprising in combination, end members each having first and second chambers, a seal between the chambers, a sealed transformer housing disposed between the members and comprising separable parts having ground abutting surfaces, conduits connecting the housing to the first chambers, conduits being sealed irom the atmosphere, an open-end, tubular member impervious to moisture and air bridged between and having its ends sealed in walls oi the second chambers, means tor supporting a lighting tube in position to extend through the tubular member in spaced relation thereto, and electrical starting means for the tube in one of the second chambers having conductors extending through the seal between the adjacent chambers.

3. In an exploslonproot lighting fixture of the type described, the combination or a rigid-walled hollow end casing having a partition therein dividing its interior into first and second chambers, a light-pervious sleeve leading outward from said second chamber and rigidly sealed to said the buter end of said sleeve, means tor supportinga fluorescent lighting tube within said sleeve in position to present an end said sleeve which is terminal adjacent the end or sealed to said casing. said partition having an aperture therein extending between said chambers, an insulating plug screwed in said aperture and completely filling the same, a conductor embedded in said plus, an electrical supply con nection in said first chamber connected to ma conductor, and an electrical connection for said terminal of the lighting tube passing through said second chamber and also connected to said conductor.

4. In an explosionproof lighting fixture oi the type described, the combination or a pair of spaced hollow and members, a light-pervious sleeve ex tending between said end members and fixedly sealed thereto with its opposite ends opening into the interiors or respective ones or said end members. means for supporting a fluorescent lighting tube within said sleeve in spaced relation to the latter, a reenforcing strut extending between said end members and flxed thereto, a transformer casing supported by said strut, a pair of rigid conductor conduits threaded at their opposite ends in said transformer casing and in respective ones of said end members, and a system of electrical supply conductors for the lighting tube for connection to its opposite ends and housed within said end members and the conduits and transformer casing.

5. An explosionproof fluorescent lighting fixture comprising, in combination. a pair of s aced and structurally separate hollow casing elements having massive explosion-resistant walls. said elements having aligned openings in their opposed portions, a rigid light-pervious sleeve extending between said elements in registry with said openings, means for supporting a fluorescent lighting tube in position to extend longitudinally through said sleeve with its end portions disthe chambers and posed in said openings, each of said casing elements having a further opening therein in its top portion closed by means of including insulating plugs, a second pair of easing elements removably fixed to the tops of respective ones of the firstmentioned pair, reeni'orcing means joining said second pair of elements, and means including conductors embedded in said plugs for establishing electrical supply connections from points within said second pair of elements to end terminals of the lighting tube within the first-mentioned pair of elements.

8. An explosionprooi fluorescent lighting fixture comprising, in combination, a pair of spaced and structurally separate hollow casing elements having massive explosion-resistant walls, said elements having aligned openings in their opposed portions, a rigid light-pervious sleeve extendin between said elements in registry with said openings, means for supporting a fluorescent lighting tube in position to extend-longitudinally through said sleeve with its end portions disposed in said openings, each of said casing elements having a further opening therein in its top portions closed by means including insulating plugs,

a second pair of easing elements removably dried to the tops of respective ones 01' the first-mentioned pair, reenforcin means Joining said second pair of elements, means including conductors embedded in said plugs for establishing electrical supply connections from points within said second pair of elements to terminals of the lighting tube within the first-mentioned pair or elements, and each of the four casing elements constitutmg said two pairs of the same having an opening herein for access to its interior and closed by to. individual threaded cover.

7. An explosionprooi fluorescent lighting fixure comprising, in combination, a pair of spaced md structurally separate hollow casing elements raving massive explosion-resistant walls, said elements having aligned openings in their opposed portions, a rigid light-pervious sleeve extending between said elements in registry with said openings, means for supporting a fluorescent lighting tube in position to extend longitudinally through said sleeve with its end portions disposed in said openings, each of said casing elements having a further opening therein in its top portion, a second pair of casing elements disposed atop respective ones of the first-mentioned pair and fixed thereto by projections on one of the superimposed elements threaded in an aperture in the other, said projections having insulating plugs extending therethrough, reenforcing means joining said second pair of elements, and means including conductors embeddedin said plugs for establishing electrical supply connections from points within said second pair of elements to end terminals of the lighting tube within the first-mentio'ned pair of elements.

8. An explosionproof fluorescent lightin fixture comprising, in combination, a pair of spaced and structurally separate hollow casing elements having massive explbsion-resistant walls, said elements having aligned openings in their opposed portions, a rigid light-pervious sleeve extending between said elements in registry with said openings, means for supporting a fluorescent lighting tube in position to tive ones of the first-mentioned pair, a reenforc ing strut rigidly Joining said second pair of elements, and a sheet metal hoo or inverted trough shape extending between said second pair of elements and removably fixed thereto, said hood being disposed above said strut with its side walls extending down below the latter to hide the same.

me A. 'I'ORNBLQM. 

